The present invention relates to aquatic plants. More particularly, the present invention relates to a system for harvesting duckweed from a body of water.
There has been an increasing interest in the use of aquatic plants as a food source or cash crop. Additionally, aquatic plants have found use in waste water treatment.
Growing and harvesting aquatic plants has become an increasingly important industry. Improving the efficiency of growth and harvest techniques is an important factor in continued expansion in the industry of aquatic plant production. U.S. Pat. No. 4,536,998 describes a system of growing aquatic plants which increases yield and the effectiveness of those plants for waste water treatment. Continued improvement of harvesting techniques is important to continued industry growth.
Aquatic plants, such as duckweed, grow near the surface of bodies of water, and tend to have a rather large volume relative to their weight, i.e., a relatively low density. However, duckweed can take on a variety of forms depending on many factors, including its life cycle stage, density and root length. In order to harvest the plant, a harvesting device must be suited to lift the duckweed in densities ranging from a thin "mono-layer" approximately 1/10 of an inch thick, to a 1"-4" thick semi-solid mat of duckweed with the consistency of mud. In the "mono-layer" state, the duckweed disburses to fill gaps on the water surface. In the "semi-solid" state, the duckweed adheres to itself resisting separation.
In the past, conveyor belt lifting systems and other such transportation mechanisms were used to transport duckweed from a pond to its final destination. Such mechanisms were sub-optimal because they resulted in poor dewatering and they were expensive and large. Thus, they were difficult to move from one site to another.